STUDY ON THE INFLUENCE OF CORROSION ON FATIGUE PROPERTIES OF THE 5.8-GRADE LOCK BOLT

In order to study the effect of corrosion on the shear fatigue properties of lock bolts, Shear fatigue tests have been conducted on 5.8-grade LMY8 lock bolts and bolts of the same specification before and after 90 days of salt spray corrosion treatment. And performed on the corrosive lock bolts are surface morphology analysis, energy dispersive X-ray spectroscopic (EDX) analysis, and fracture morphology analysis. The results show that: due to the interference fit between the collar and the lock bolt rod, the lock bolt has good corrosion resistance, the fatigue life of the lock bolts after corrosion is only reduced by 6.57% lower than that of the corrosion treated bolts by 74.47%. The corrosion degree of the polished rod of the lock bolt after corrosion is light, but there are many corrosion pits, which will affect the mechanical properties of the lock bolt. The fatigue fracture of the lock bolt after corrosion changes in the fatigue source, propagation, and transient breaking area, and the main reason is that the corrosion pit of the lock bolt rod makes the fatigue process exhibit more obvious brittleness. Therefore, shear lip can be observed for uncorroded lock bolts, while it is not observed for corroded lock bolts.